This proposal is to purchase JEM-100CXII TEMSCAN electron microscope to replace a 14-year-old TEM. Forsyth Dental Center is the foremost independent center for research and advanced study in dentistry. In order to maintain high standards of achievement in a wide variety of research endeavors it is periodically necessary to update and expand the capabilities of existing instrumentation; particularly that equipment utilized by many researchers representing ten departments within the institute. These departments include the following areas of research: amelogenesis, several specific aspects of microbial ecology pertaining to dental disease, identification of microbiota associated with periodontal health and disease, periodontal therapy by local drug delivery, effects of fluoride on plaque, replacement therapy of dental caries, enamel solubility and remineralization, and the properties of bone in aging. Additionally, there are several graduate student projects pertaining to differentiation and growth of bone, aging of salivary glands, and dental materials currently in progress. Finally electron microscopy is used by several investigators on projects in preliminary stages of experimentation pending future funding. The ease of the JEM-100CX to select TEM bright field, dark field, STEM, and SEM secondary or backscatter, with high resolution in each mode, greatly facilitates operation procedures. Rapidity and ease of instrument operation is important to both user and operator in overcoming time constraints in using the EM in many experiments, including quality control of samples involving long procedures (e.g. plasmid isolation and characterization). The versatility to view a sample in various modes enhances and reinforces concepts and images acquired by single mode operation.